Field of the Invention
This invention relates to particulate collection and cooling in a turbomachine particularly the type of turbomachine known as a power expander. In many processes, high temperature often times wasted, gases containing high concentrations of solid materials thus rendering the gases suitable for use as a working fluid within a turbine or such other power recovery equipment are utilized. The present invention concerns recovering energy from this working fluid.
Due to the increasing energy shortage, methods of recovering heretofore wasted energy are being looked towards as a potential source of power. A typical process which produces a great deal of energy that is normally wasted is found in the coal gasification industry. In coal gasification, high temperature exhaust gases are generated as a byproduct of the process. Because of the nature of the process, these hot gases contain a very high percentage of solid waste materials in the form of fly ash, dolomite and the like.
The use of this potentially high energy source in power recovery equipment has proven difficult because the recovery equipment is subjected to catastrophic failure resulting from blade erosion under the action of solid waste particles and/or material fatigue caused by high operating temperatures. Furthermore, to compound difficulties it has been found that the erosion rate increases with increases in gas temperatures.
Another process in which particulates are found in high energy gases is the fluid catalytic cracking process found in the petroleum industry. The catalyst may be entrained in the hot gas stream such that it enters the expander as a particulate thereby contributing to blade erosion.
In order to obtain maximum efficiency, the gas must be used at the hottest temperature possible. Special alloys are necessary if components are in contact with gases above the 1250.degree. F. to 1300.degree. F. range and are allowed to become heated to this temperature range. In order to avoid the expense of utilizing alloys which retain their strength at these high temperatures it is necessary to cool the materials involved to allow the use of less expensive, more workable materials.